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§2395.81. Water Pipe Electrode.

GROUNDING ELECTRODES

Where available on the premises, a metal underground water pipe shall always be used as the grounding electrode, regardless of its length and whether supplied by a community or a local underground water piping system or by a well on the premises. Where the buried portion of the water pipe (including any metal well casing effectively bonded to the pipe) is less than 10 feet long or where the water pipe is or is likely to be isolated by insulated sections or joints so that the effectively grounded portion is less than 10 feet long, it shall be supplemented by the use of an additional electrode of a type specified by Section 2395.82 or Section 2395.83. The interior metal cold water piping system shall always be bonded to the service-equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used.

NOTE: Expanding use of nonmetallic piping for water systems and insulating couplings on metal water systems makes it more important that water piping within a building be adequately grounded without depending on connections to an outside piping system.